Collectors are known from U.S. Pat. No. 6,507,440 B1, DE 10 2010 063 530 A1, WO 2011/138259 A1, from U.S. Pat. No. 7,075,712 B2, U.S. Pat. No. 7,501,641 B2, US 2006/0176547 A1, US 2006/0120429 A1, U.S. Pat. No. 7,075,713 B2, EP 1 469 349 A1, US 2008/0266650 A1, WO 2007/045 434 A2, U.S. Pat. No. 6,438,199 B1, U.S. Pat. No. 5,339,346 A, EP 1 650 786 B1, DE 10 2011 084 266 A and WO 2013/053 692 A.